1. Field
The following description relates to a technique for data transfer in a server-based computing environment, and more particularly, to a method of minimizing a transmission delay time while maintaining a session between a client terminal and a server, when a USB device connected to the client terminal is recognized by the server and data transmission/reception between the USB device and the server is performed.
2. Description of the Related Art
A client terminal can receive the execution results by a resource of a server by connecting to the server through a remote access protocol. In other words, a client terminal receives a screen of displaying the execution results of application programs executed by a server, from the server, through a remote access protocol. At this time, the computing resource of the client terminal is reduced, and accordingly the price of the client terminal is lowered.
Also, in video multi-conferencing, video calling, etc., a client terminal can transmit data received from an external device to a server, and the server can process the received data and transmit a screen including the results of the processing to other client terminals. For data transmission/reception between a server and an external device connected to a client terminal, the server identifies an external device connected to the client terminal, and allocates a logical virtual channel to the identified external device to thereby provide an independent communication method for data transmission/reception. A general remote access protocol classifies virtual channels into static virtual channels and dynamic virtual channels according to their characteristics. The dynamic virtual channels are used when an external device connected to a client through a USB interface is dynamically plugged in or unplugged from the client. When data stored in a USB device is transmitted through a dynamic virtual channel, a bandwidth may be adjusted according to the number of dynamic virtual channels.
There are the case where a server writes data in a USB device (e.g. storage having a file system) connected to a client, the case where a USB device (e.g. a PC camera) connected to a client transmits data to a server, etc. In order to transmit/receive data stored in a USB device connected to a client to/from a server, as a communication protocol for USB device, Remote Desktop Protocol (RDP) Extension has been proposed.
A conventional technology for communication between USB devices and a server is disclosed in Korean Patent Application No. 10-2005-0113510, entitled “USB Devices in Application Server Environments”, filed on Nov. 25, 2005, by Microsoft Corporation.